Download HIGH-RATE REACTIVE SPUTTERING OF DIELECTRIC

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EP 2 770 083 B1
EUROPEAN PATENT SPECIFICATION
(12)
(45) Date of publication and mention
(51) Int Cl.:
C23C 14/00 (2006.01)
C23C 14/54 (2006.01)
of the grant of the patent:
18.11.2015 Bulletin 2015/47
C23C 14/08 (2006.01)
(21) Application number: 13155936.1
(22) Date of filing: 20.02.2013
(54) HIGH-RATE REACTIVE SPUTTERING OF DIELECTRIC STOICHIOMETRIC FILMS
HOCHLEISTUNG REAKTIVES SPUTTERN VON DIELEKTRISCHEN STÖCHIOMETRISCHEN
FILMEN
PULVÉRISATION CATHODIQUE RÉACTIVE À HAUT DÉBIT POUR FILMS STOECHIOMÉTRIQUES
DIÉLECTRIQUES
(74) Representative: Kohler Schmid Möbus
(84) Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB
GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO
PL PT RO RS SE SI SK SM TR
Patentanwälte
Partnerschaftsgesellschaft mbB
Ruppmannstraße 27
70565 Stuttgart (DE)
(43) Date of publication of application:
27.08.2014 Bulletin 2014/35
(73) Proprietors:
• University of West Bohemia in Pilsen
306 14 Pilsen (CZ)
• TRUMPF Huettinger Sp. Z o. o.
05-220 Zielonka (PL)
(72) Inventors:
EP 2 770 083 B1
• Bugyi, Rafal
00264 Warszawa (PL)
• Vlcek, Jaroslav
326 00 Plzen (CZ)
• Rezek, Jiri
323 00 Plzen (CZ)
• Lazar, Jan
387 06 Malenice (CZ)
(56) References cited:
EP-A1- 1 553 206
WO-A1-2009/071667
WO-A1-2007/147582
WO-A1-2010/125002
• MARTIN N ET AL: "High rate and process control
of reactive sputtering by gas pulsing: the Ti-O
system", THIN SOLID FILMS, ELSEVIERSEQUOIA S.A. LAUSANNE, CH, vol. 377-378, 1
December 2000 (2000-12-01) , pages 550-556,
XP004226750, ISSN: 0040-6090, DOI:
10.1016/S0040-6090(00)01440-1
• LAZAR J ET AL: "Ion flux characteristics and
efficiency of the deposition processes in high
power impulse magnetron sputtering of
zirconium", JOURNAL OF APPLIED PHYSICS,
AMERICAN INSTITUTE OF PHYSICS, 2
HUNTINGTON QUADRANGLE, MELVILLE, NY
11747, vol. 108, no. 6, 28 September 2010
(2010-09-28), pages 63307-63307, XP012142869,
ISSN: 0021-8979, DOI: 10.1063/1.3481428
Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent
Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the
Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been
paid. (Art. 99(1) European Patent Convention).
Printed by Jouve, 75001 PARIS (FR)
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EP 2 770 083 B1
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] This application relates generally to a reactive
sputtering method and apparatus, and more specifically
to a method and apparatus for establishing a high-rate
deposition of dielectric stoichiometric films and minimizing arcing appearing between a target and an anode or
other portion of the vacuum system.
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2. Description of Related Art
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[0002] Dielectric films (particularly oxides and nitrides)
are widely used in a broad range of applications such as
semiconductor chips, magnetic and optical recording, flat
panel displays, ink jet printer heads, solar cells, integrated optics, optical films and hard protective films. Reactive
magnetron sputtering which involves sputtering a metal
target in argon-oxygen or argon-nitrogen gas mixtures is
a commonly used deposition method to produce these
films. However, control of such a reactive sputtering process to both maximize the rate of deposition or film formation and to achieve a proper film stoichiometry has
been difficult to accomplish.
[0003] Reactive sputtering is a very versatile coating
technique that allows the preparation of a wide variety of
compound materials. However, it has traditionally had
one major drawback. When the partial pressure of the
reactive gas (e.g., oxygen or nitrogen) reaches the right
level to form a stoichiometric film of the metal compound
(e.g., oxide or nitride) on the surface of a substrate, it
also forms the same metal compound on the surface of
the metal target. This, in turn, results in a substantially
reduced deposition rate of the films due to low sputtering
yield of the metal atoms from the compound part of the
metal target. In addition, considerable arcing, leading to
a low quality of the deposited films, can be observed on
the target under these conditions at high target power
densities applied (e.g., during high power impulse magnetron sputtering). Arcing indicates the generation of
short circuits between the target (cathode) and an anode
or electric ground of vacuum system, caused by the buildup of insulating films on the target. There are two "modes"
of operation for reactive sputtering of a metal target to
deposit a compound film. For low flow rate of the reactive
gas into the vacuum chamber, the target remains metallic. For high flow rate of the reactive gas, the target is
covered by the compound. Much higher (usually 5 to 10
times) deposition rates are achieved in the "metallic
mode" than in the "covered (poisoned) mode". As the
reactive gas flow rate is varied, there is a transition between the metallic mode and the covered mode exhibiting
hysteresis; i.e., the difference in the deposition rate (and
the target voltage) depending on whether a specific sputtering state is entered from the metallic mode or from the
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covered mode under otherwise identical process conditions. To form high-quality dielectric stoichiometric films
at high rate, reactive sputtering has to operate in the transition region between the metallic and covered mode.
[0004] A recent development of the well established
magnetron sputtering technique is the high power impulse magnetron sputtering (HiPIMS) which is characterized by target power densities on the order of kWcm-2
applied during short voltage pulses (typically 40 ms to
200 ms). The high target power density leads to the generation of very dense discharge plasmas with high degrees of ionization of sputtered atoms. Consequently,
film deposition can be carried out at highly ionized fluxes
of the target material atoms. This is of significant interest
for directional deposition into high aspect ratio trench and
via structures, for substrate-coating interface engineering and ion-assisted growth of films. In spite of several
successful applications of these systems to reactive sputter depositions of dielectric films, there are still substantial
problems with arcing during the deposition processes at
high target power densities and with low deposition rates
achieved.
[0005] Accordingly, there is a need in the art of HiPIMS
for a method and apparatus providing effective and reliable control of the reactive sputtering process to achieve
high-rate deposition of dielectric stoichiometric films with
minimized arcing.
[0006] WO 2007/147582 A1 relates to the control of a
reactive high-power pulsed sputter process. A method
for controlling a process of the aforementioned kind is
described, wherein a controlled variable is measured and
an adjustable variable is modified based on the measured controlled variable in order to adjust the controlled
variable to a predetermined setting value. In particular,
the discharge capacity is modified by varying the pulse
frequency of the discharge.
[0007] WO 2009/071667 A1 discloses a method and
apparatus for sputter depositing an insulation layer onto
a surface of a cavity formed in a substrate and having a
high aspect ratio. A target formed at least in part from a
material to be included in the insulation layer and the
substrate are provided in a substantially enclosed chamber defined by a housing. A plasma is ignited within the
substantially enclosed chamber and a magnetic field is
provided adjacent to a surface of the target to at least
partially contain the plasma adjacent to the surface of
the target. A voltage is rapidly increased to repeatedly
establish high-power electric pulses between a cathode
and an anode. An operational parameter of the sputter
deposition is controlled to promote sputter depositing of
the insulation layer in a transition mode between a metallic mode and a reactive mode.
[0008] WO 2010/125002 A1 discloses an apparatus
for coating a substrate by reactive sputtering which comprises an axis, at least two targets in an arrangement
symmetrically to said axis and a power supply connected
to the targets, wherein the targets are alternatively operable as cathode and anode.
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[0009] In EP 1 553 206 A1 a method for reactive sputtering is disclosed, in which a reactive sputtering apparatus including a sputtering vaporization source provided
with a metal target disposed in a vacuum chamber , a
sputtering power source to drive the sputtering vaporization source, and an introduction mechanism to introduce
an inert gas for sputtering and a reaction gas for forming
a compound with sputtered metal into the vacuum chamber is used, and reactive sputtering film formation is performed on a substrate disposed in the above-described
vacuum chamber, wherein the method includes the steps
of performing constant-volt-age control to control the voltage of the above-described sputtering power source at
a target voltage and, in addition, performing target voltage control at a control speed lower than the speed on
the above-described constant-voltage control, the target
voltage control operating the above-described target
voltage in order that the spectrum of plasma emission
generated forward of the above-described sputtering vaporization source becomes a target value.
[0010] Martin, N. et al.: "High rate and process control
of reactive sputtering by gas pulsing: The Ti-O system",
THIN SOLID FILMS, vol. 377 - 378, (2000-12-01), pages
550 - 556, discloses depositing titanium oxide thin films
by DC reactive magnetron sputtering from a pure titanium
target in a mixture of Ar+O2. The reactive gas was injected with a controlled pulsed technique. A constant pulsing
period was used for every deposition whereas the O2
injection time was changed systematically.
[0011] Lazar, J. et al.: "ion flux characteristics and efficiency of the deposition processes in high power impulse magnetron sputtering of zirconium", JOURNAL OF
APPLIED PHYSICS, AMERICAN INSTITUTE OF
PHYSICS,
2
HUNTINGTON
QUADRANGLE,
MELVILLE, NY 11747, vol. 108, no. 6, (2010-09-28), pages 63307 - 63307 discloses high power impulse magnetron sputtering at a constant argon pressure.
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BRIEF SUMMARY
40
[0012] The present invention overcomes the above
mentioned problems, even when high power impulse
magnetron sputtering a metal target is used, by providing
a reactive sputtering processing system and method that
controls a pulsed reactive gas flow rate into a vacuum
chamber at a constant target voltage, kept by a power
supply, to promote a high-rate deposition of dielectric stoichiometric films in a transition region between a metallic
mode and a covered (poisoned) mode.
[0013] For a given target material and reactive process
gas, one of the two process parameters (namely, the
target current, alternatively the average target current in
a period of a pulsed power supply, or the reactive gas
partial pressure in the vacuum chamber), which are simultaneously monitored in time by a process controller,
is selected as a control process parameter. For a given
nominal target power, and the target material and the
reactive process gas, an optimized constant target volt-
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age, non-reactive gas (argon) partial pressure, total reactive gas flow rate into the vacuum chamber and configuration of the reactive gas conduit system, together
with a critical value of the control process parameter selected, are determined empirically using the apparatus
controlling the reactive sputtering process on the basis
of the sensed time-dependent values of the control parameter. This determination is based on measurements
of the deposition rates and characterization of the films
deposited. The critical value of the control parameter defines a range of the reactive gas partial pressure in the
chamber through the controlled pulsed reactive gas flow
rate into the chamber allowing to perform a stabilized
high-rate reactive magnetron deposition of dielectric stoichiometric films in a transition region between a metallic
mode and a covered (poisoned) mode.
[0014] An important aspect of the present invention is
that the method and apparatus designed make it possible
to utilize benefits of the HiPIMS discharges with target
power densities of up to several kWcm-2 during short
target voltage pulses (typically 40 ms to 200 ms) in highrate depositions of dielectric stoichiometric films.
[0015] In particular the invention relates to a method
for controlling a magnetron sputter deposition process
involving reaction between reactive gas species and a
material included in a target acting as a cathode, said
method comprising the steps of:
selecting a control process parameter for a given
target material and reactive process gas;
establishing an operation regime for a reactive sputter deposition process for a given nominal target
power level; and
performing a stabilized reactive deposition of dielectric stoichiometric films at high rates in a transition
region between a metallic mode and a covered mode
through a controlled pulsed reactive gas flow rate
into the vacuum chamber;
sensing time-dependent values of said control process parameter and providing a signal to mass flow
controllers to adjust the pulsed reactive gas flow rate
into the vacuum chamber on the basis of the sensed
time-dependent values.
[0016] The transition region between metallic mode
and covered mode may be determined based on a range
of the reactive gas partial pressure in the vacuum chamber defined using the said critical value of the said control
process parameter.
[0017] The target may be a metal and a compound
formed from the reaction may be a dielectric stoichiometric material.
[0018] The sputter deposition of a compound onto a
substrate may be performed at a rate at least about 40%
of a rate of deposition of the target material in a metallic
mode corresponding to operating without the presence
of said reactive gas at substantially the same power conditions.
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EP 2 770 083 B1
[0019] The compound may be selected from the group
consisting of oxides, nitrides, oxynitrides, carbides,
sulfides, fluorides, chlorides, borides, and mixtures
thereof.
[0020] The control process parameter may be the target current in case of continuous DC sputtering , or the
average target current in a period of a pulsed power supply in case of pulsed sputtering, or the reactive gas partial
pressure in a vacuum chamber.
[0021] The sensitivity of the target current in case of
continuous DC sputtering, or of the average target current in a period of a pulsed power supply in case of pulsed
sputtering, and of the reactive gas partial pressure in a
vacuum chamber to constant flow rate pulses of the reactive gas into the vacuum chamber at a constant target
voltage under the same discharge conditions is determined. In other words, process characterization is carried
out and it is determined how the parameters mentioned
above respond to constant flow rate pulses of the reactive
gas into the vacuum chamber at a constant target voltage
under the same discharge conditions.
[0022] The parameter showing the highest sensitivity
to constant flow rate pulses of the reactive gas into the
vacuum chamber at a constant target voltage under the
same discharge conditions may be selected as control
process parameter.
[0023] The operation regime may be established
based on determining an (optimized) constant target voltage, non-reactive gas, for example argon, partial pressure, total reactive gas flow rate into the vacuum chamber
and configuration of the reactive gas conduit system, together with a critical value of the control process parameter selected, such that a given deposition rate and desired physical properties of films formed are achieved at
arcing below a given level.
[0024] This results in high deposition rates and desired
elemental compositions and physical properties of films
formed at a minimized arcing. The determination of the
above quantities is based on fundamental knowledge in
the art of reactive magnetron sputtering, on measurements of the deposition rates, on characterization of the
films deposited and on detection of discharge instabilities
(arcs).
[0025] The critical value of the control process parameter may be used to define the times of terminations and
successive initiations of preset constant reactive gas flow
rate pulses into the vacuum chamber.
[0026] The target power may be supplied at a constant
target voltage using a DC power supply or at a constant
target voltage during discharge pulses using a pulsed
power supply, including a high power pulsed DC power
supply with target power densities of up to several
kWcm-2 in short target voltage pulses.
[0027] The invention also relate to a reactive sputter
deposition apparatus, comprising:
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a reactive gas source that provides a reactive gas
into the vacuum chamber, the reactive gas characterized by a given pulsed flow rate into the chamber,
maintained by mass flow controllers, or by a given
partial pressure in the chamber, determined from a
total gas pressure in the chamber measured at a
fixed preset value of the non-reactive gas partial
pressure;
a target as a cathode in the vacuum chamber and
including a material to be combined with reactive gas
species to form a compound, wherein the cathode
is part of a magnetron sputter source,
a power supply electrically coupled to said target
such that said target may be selectively powered by
the power supply to generate a discharge plasma in
the chamber with the reactive gas species that combine with the material of the target to form the compound;
a control device that senses time-dependent values
of said control process parameter and is configured
to provide a signal to said mass flow controllers to
adjust a pulsed reactive gas flow rate into the vacuum
chamber at a constant value of the non-reactive gas
partial pressure to perform a stabilized reactive deposition of dielectric stoichiometric films at high rates
and a minimized arcing in a transition region between
a metallic mode and covered mode.
[0028] Said target may be a metal and said compound
may be a dielectric stoichiometric material.
[0029] The control device may be configured to allow
simultaneous monitoring in time both the reactive gas
partial pressure in said vacuum chamber, and either the
target current in case of continuous DC sputtering or the
average target current in a period of a pulsed power supply in case of pulsed sputtering to select one of them as
said control process parameter for a given target material
and reactive process gas on the basis of a higher sensitivity of one of these quantities to constant flow rate pulses of said reactive gas into said vacuum chamber at a
constant target voltage under the same discharge conditions.
[0030] The power supply may be a DC power supply
operating at a constant target voltage or a pulsed power
supply operating at a constant target voltage during discharge pulses, including a high power pulsed DC power
supply with target power densities of up to several
kWcm -2 in short target voltage pulses, the pulsed power
supplies possessing an internal or external computer
control allowing to evaluate a time-dependent average
target current in a period of the pulsed power supply during the reactive gas flow rate pulsing.
BRIEF DESCRIPTION OF THE DRAWINGS
55
[0031] The invention may take physical form in certain
parts and arrangement of parts, embodiments of which
will be described in detail in this specification and illus-
a vacuum chamber;
an anode;
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EP 2 770 083 B1
trated in the accompanying drawings which form a part
hereof and wherein:
FIG. 1 schematically depicts component parts of a
sputtering system which may be used to practise the
present invention;
FIGS. 2A and 2B show waveforms of the target voltage and the target current density for a fixed average
target power density of 50 Wcm-2 in a period and
voltage pulse duration of 50 ms during a controlled
reactive HiPIMS of ZrO2 and Ta2O5 films, respectively, and
FIGS. 3A and 3B show the deposition rate as a function of the duty cycle, together with the corresponding extinction coefficient and refractive index of ZrO2
and Ta2O5 films, respectively, for a fixed average
target power density of 50 Wcm -2 in a period.
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DETAILED DESCRIPTION OF THE INVENTION
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[0032] The method and associated apparatus of the
present invention are designed to control and preferably
optimize the conditions for interaction between target material atoms and reactive gas atoms and molecules on
the target surface, on the surface of growing films and in
the discharge plasma during reactive high power magnetron sputtering (particularly HiPIMS) a metal target such
that high quality dielectric stoichiometric films may be
deposited at high deposition rates.
[0033] Referring to FIG. 1, there are schematically depicted component parts of a sputtering system which may
be used to practise the invention. A vacuum chamber 10
is evacuated by a pump 12 after a substrate material 14
(e.g., silicon wafer, glass, steel, etc.) is mounted on a
holder 16 within the chamber 10. A target material 18
(e.g., zirconium, tantalum or some other metal) is also
mounted within the chamber 10. The target 18 serves as
a cathode in the process, and the inside walls of chamber
10 serve as anode. Preferebly, as known in the art, the
cathode is a part of the magnetron sputter source (a detailed structure not shown).
[0034] A non-reactive gas (e.g., inert gas, p. ex. argon)
is admitted to chamber 10 from a source 20 via a mass
flow controller 22, shut-off valve 24, and conduit. A reactive gas (e.g., oxygen, nitrogen, methan, acetylene, etc.)
is provided from a source 26 through mass flow controllers 28 and 30, shut-off valves 32 and 34, and via conduits
36 and 38 located generally at two different positions in
front of the sputtered target to reduce the target coverage
by a compound particularly during a high power magnetron sputtering process, when the degree of dissociation
of the reactive gas molecules is significantly increased
not only in the flux onto the substrate but also in the flux
onto the target. In an alternative embodiment, the reactive gas source 26 may be replaced by two sources of
different reactive gases (e.g., oxygen and nitrogen) to
reactively sputter deposit ternary compounds (e.g., oxynitrides or mixtures of oxide and nitride material phas-
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es). A pressure sensor 40 measures the total pressure
in the vacuum chamber at a fixed preset value of the
argon partial pressure, kept by mass flow controller 22.
A process controller 42 (preferably a programmable logical controller) provides a control signal to the mass flow
controllers 28 and 30 on the basis of sensed time-dependent values of either the target current (alternatively,
the average target current in a period, which may be evaluated by a computer controlling the operation of a pulsed
power supply 44 used), e.g., for sputter deposition of
ZrO2 films, or the total pressure in vacuum chamber determined by the pressure sensor 40 (e.g., for sputter deposition of Ta2O 5 films), as will be further explained below.
[0035] The power supply 44 provides power to target
18 (e.g., by an electrically conductive connection of a
cathode terminal conductor to the target, the target thus
acting as part of the cathode when so connected). In a
preferred embodiment of the present invention, a high
power pulsed DC power supply 44 with arc handling capabilities (a fast arc detection and suppression technique) provides short (typically 40 ms to 200 ms) negative
constant-voltage pulses at the target with target power
densities on the order of kWcm -2 and a typical duty cycle
(ratio of the voltage pulse duration to the period duration)
in the range from 2 % to 10 %, as is known in the art of
HiPIMS. Alternative implementations of the present invention may employ various continuous DC, pulsed or
RF power supplies as the power supply 44, such target
power supply techniques being generally known in the
art.
[0036] Accordingly, in accordance with the basic, wellknown operation of a reactive sputtering process, reactive and non-reactive gases flow into the chamber, and
power supplied to the cathode provides an electric potential between the cathode and the anode, thus generating a discharge plasma in the chamber. The plasma
includes non-reactive gas atoms and ions, reactive gas
atoms, molecules and ions, and sputtered target material
atoms and ions, particularly at high target power densities. A source of metal atoms for deposition on substrate
is their sputtering from the target due to its ion bombarding. The main source of reactive gas for deposition on
the substrate is its flow into the vacuum chamber, which
is related to the reactive gas partial pressure. In addition,
reactive gas species can react with the target material at
the target surface to form a compound on the target (e.g.,
oxidize the target). Such compound formation on the target is well recognized as a primary problem in reactive
sputtering, and is particularly a problem in reactive sputtering of metal targets to produce dielectric stoichiometric
films at high deposition rates.
[0037] In accordance with the present invention, process controller 42 provides a control signal to the mass
flow controllers 28 and 30 to adjust the pulsed reactive
gas flow rate into the chamber (by a duration of preset
constant gas flow rate pulses) such that the reactive gas
flow rate, which is related to the reactive gas partial pressure in the chamber, is maintained within a certain spec-
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EP 2 770 083 B1
ified range. This range of the reactive gas flow rate into
the chamber (and the reactive gas partial pressure in the
chamber) is determined based on a process development procedure as follows.
[0038] First, for a given target material and reactive
process gas (or gases), one of the two process parameters (namely, the target current, alternatively the average target current in a period of a pulsed power supply,
or the total pressure in the chamber at a fixed preset
value of the argon partial pressure, i.e., the reactive gas
partial pressure in the chamber), which are simultaneously monitored in time by process controller 42, is selected as a control process parameter on the basis of a
higher sensitivity of one of these quantities to constant
flow rate pulses of the reactive gas into the vacuum chamber at a constant target voltage (alternatively, a constant
target voltage during discharge pulses) under the same
discharge conditions. As is known in the art, a different
behavior of various target materials is mainly caused by
their different affinities for chemical reactions with reactive gases on target surfaces and by different, or even
opposite, dependences of the secondary electron emission coefficients for partly covered targets (e.g., by oxides
or nitrides) on the target coverage.
[0039] Second, for a given nominal target power, and
the target material and the reactive process gas, an optimized constant target voltage, non-reactive gas (argon)
partial pressure, total reactive gas flow rate in both conduits 36 and 38 and its dividing into them, as well as the
locations of the conduits in front of the target and directions of the reactive gas flow from them (e.g., towards
the target or substrate), together with a critical value of
the control process parameter selected (the average target current in a period for sputter deposition of ZrO2 films
and the oxygen partial pressure for sputter deposition of
Ta2O5 films in FIGS. 2A and 2B, respectively), are determined using the apparatus controlling the reactive
sputtering process on the basis of the sensed time-dependent values of the control parameter. This determination is based on fundamental knowledge in the art of
reactive magnetron sputtering and on measurements of
the deposition rates and characterization of the films deposited (particularly optical transparence, elemental
composition, hardness, mass density, structure and surface morphology). The critical value of the control parameter defines a range of the reactive gas partial pressure
in the chamber allowing to perform a stabilized high-rate
reactive magnetron deposition of dielectric stoichiometric
films in a transition region between a metallic mode and
a covered (poisoned) mode. When a value of the monitored control parameter becomes to be higher that the
corresponding critical value, the process controller 42
provides a signal to the mass flow controllers 28 and 30
to switch off the reactive gas flow into the vacuum chamber, and thus to minimize arcing on a compound part of
the metal target and to avoid a substantial reduction in
the deposition rate of films. After a continuing increase
in the control parameter, mainly due the "inertia" associ-
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ated with changes in the reactive gas partial pressure in
the chamber, the values of the control parameter decrease (as shown in FIGS. 2A and 2B). When an instantaneous value of the control parameter becomes to be
equal to or less than its critical value, the process controller 42 provides a signal to the mass flow controllers
28 and 30 to switch on the reactive gas flow into the
vacuum chamber, and thus to achieve a sufficient incorporation of the reactive gas atoms into the films (stoichiometric composition). This procedure of establishing the
operation regime for a stabilized reactive deposition of
dielectric stoichiometric films at high rates may be repeated for various nominal powers.
[0040] In addition to various alternative implementations of the present invention with the use of standard
"low power" continuous DC, pulsed or RF power supplies
with a usual target power density less than 20 Wcm -2 as
the power supply 44, it is particularly useful for high-rate
deposition of dielectric stoichiometric compounds using
high power magnetron sputtering a metal target, including high power impulse magnetron sputtering (HiPIMS)
with target power densities of up to several kWcm -2 in
short target voltage pulses (typically 40 ms to 200 ms).
Application of the pulsed reactive gas flow control according to the present invention with the use of a commercially available high power pulsed DC power supply
possessing the following features, (i) production of negative voltage pulses at an essentially constant value (the
so-called constant-voltage mode of operation), (ii) effective arc handling capabilities (a fast arc detection and
suppression technique), and (iii) a computer control able
to evaluate the time-dependent average target current in
a period of the pulsed power supply during the reactive
gas flow rate pulsing (as shown in FIG. 2A), makes it
possible to utilize benefits of the HiPIMS discharges,
known in the art. These are very high total ion fluxes to
the target during voltage pulses leading to intense sputtering of metal atoms from a metallic fraction at the target
and of reactive gas atoms from a compound fraction at
the target, reducing the target coverage by the compound, and thus increasing the deposition rate of films.
In addition, the fluxes of the reactive gas atoms and molecules to the target during the voltage pulses are substantially reduced by a strong "sputtering wind" of the
sputtered atoms resulting in a rarefaction of the gas mixture in front of the target. High degrees of dissociation of
the reactive gas molecules in the flux onto the substrate
lead to a higher deposition rate of films and to a higher
incorporation of the reactive gas atoms into the films due
to a much higher sticking coefficient of the reactive gas
atoms at the substrate surface compared to the reactive
gas molecules. Moreover, much higher total ion fluxes
to the substrate result in subplantation of the reactive gas
atoms into the growing films and in their densification.
[0041] Process controller 42 may be implemented in
various ways, but a programmable logical controller or a
programmed digital computer (e.g., personal computer
or workstation) with data acquisition and control interfac-
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EP 2 770 083 B1
es are preferred. It may be understood to incorporate the
process controller 42 into the power supply 44 itself.
[0042] The following example of experimental results
obtained in developing and implementing reactive sputter deposition processes for ZrO2 and Ta2O5 films in accordance with the hereinabove described embodiments
is merely provided by way of example to illustrate features
and characteristics of the present invention, which is not
to be construed as being limited thereby.
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EXAMPLE
[0043] The experiments were performed using a
strongly unbalanced magnetron source with a directly
water-cooled planar zirconium or tantalum target (99.9
% Zr and Ta purity, diameter of 100 mm and thickness
of 6 mm) in a standard stainless-steel vacuum chamber
(diameter of 507 mm and length of 520 mm), which was
evacuated by a diffusion pump (2 m3s-1) backed up with
a rotary pump (30 m3h-1). The base pressure before deposition was 10-3 Pa. The total pressure of the argon-oxygen gas mixture was around 2 Pa.
[0044] The magnetron was driven by a high power
pulsed DC power supply (HMP 2/1, Hüttinger Elektronik).
The repetition frequency was 500 Hz and the voltage
pulse duration ranged from 50 ms to 200 ms with the corresponding duty cycle from 2.5 % to 10 %. The ZrO 2 and
Ta2O5 films were deposited on silicon substrates at a
floating potential. The target-to-substrate distance was
100 mm. The film thickness (typically between 800 nm
and 1200 nm) was measured by profilometry (Dektak 8
Stylus Profiler, Veeco). The substrate temperatures were
less than 300 °C during depositions. The elemental composition of the films was measured by a PANalytical
wavelength-dispersive X-ray fluorescence spectrometer
MagiX PRO with a calibration performed by Rutherford
backscattering spectrometry. Structure of the films was
investigated using a PANalytical X’Pert PRO diffractometer. The refractive index and extinction coefficient were
determined by variable angle spectroscopic ellipsometry
using the J.A.Woollam Co. Inc. instrument. Film hardness was determined using a computer-controlled microhardness tester (Fischerscope H-100B) with a preset
maximum load of 20 mN.
[0045] FIGS. 2A and 2B show time evolutions of the
target voltage and the target current density for a preset
average target power density of 50 Wcm -2 in a period
and voltage pulse duration of 50 ms, together with the
corresponding time evolutions of the average target current in a period (at a preset argon partial pressure of 2
Pa) and the oxygen partial pressure (at a preset argon
partial pressure of 1.5 Pa) controlling the oxygen flow
rate pulses during reactive sputter depositions of highly
transparent, stoichiometric ZrO2 and Ta2O5 films, respectively. Note that the shown values of the oxygen flow
rate represent the total oxygen flow rates in conduits 36
and 38 located 20 mm and 40 mm from the target, respectively, during the deposition of the ZrO2 films, and
15
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12
20 mm from the target during the deposition of the Ta2O5
films (FIG. 1). The ratios between the oxygen flow rates
in the conduits 36 and 38 were 5:2 with the flows directed
to the substrate for the deposition of the ZrO2 films and
1:1 with the flows directed to the target for the deposition
of the Ta2O5 films. As can be seen in FIGS. 2A and 2B,
the average target power density in a pulse ranges from
1.70 kWcm-2 to 2.10 kWcm-2, and from 1.71 kWcm-2 to
2.02 kWcm-2 for the controlled depositions of the ZrO2
and Ta2O5 films, respectively, between the corresponding minimum and maximum oxygen partial pressures allowed by the process controller 42.
[0046] FIGS. 3A and 3B show the deposition rates of
films and the average target power densities in a pulse,
together with the extinction coefficients, k, and the refractive indexes, n, of the films measured at 550 nm, for
a fixed average target power density of 50 Wcm-2 in a
period and various voltage pulse durations in the range
from 50 ms to 200 ms during depositions with the corresponding duty cycles from 2.5 % to 10 %. The fixed argon
partial pressure was 2 Pa for all the depositions of the
ZrO2 films, while it ranged from 1.5 Pa for the 50 ms voltage pulses to 1 Pa for the 200 ms voltage pulses at the
depositions of the Ta2O5 films. As can be seen, very high
deposition rates have been achieved for both the stoichiometric ZrO 2 and Ta2O5 films. They are highly optically
transparent and densified (mass density of up to 95 %
of that for the respective bulk material). The ZrO2 films
are crystalline (a monoclinic phase), while the Ta2O5
films are nanocrystalline (as expected at the substrate
temperature less than 300 °C). Their hardness ranges
from 10 GPa to 16 GPa, and from 7 GPa to 8 GPa, respectively.
[0047] Although the above description provides many
specificities, these enabling details should not be construed as limiting the scope of the invention, and it will
be readily understood by those persons skilled in the art
that the present invention is susceptible to many modifications and equivalent implementations without departing from this scope and without diminishing its advantages. It is therefore intended that the present invention is
not limited to the disclosed embodiments but should be
defined in accordance with the claims which follow.
45
Claims
1.
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7
A method for controlling a magnetron sputter deposition process involving reaction between reactive
gas species and a material included in a target (18)
acting as a cathode, said method comprising the
steps of:
selecting a control process parameter for a given
target material and reactive process gas;
establishing an operation regime for a reactive
sputter deposition process for a given nominal
target power level; and
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performing a reactive deposition of dielectric
stoichiometric films in a transition region between a metallic mode and a covered mode
through a controlled pulsed reactive gas flow
rate into the vacuum chamber (10);
sensing time-dependent values of said control
process parameter and providing a signal to
mass flow controllers (28, 30) to adjust the
pulsed reactive gas flow rate into the vacuum
chamber (10) on the basis of the sensed timedependent values.
2.
3.
The method according to claim 1, wherein said target
(18) is a metal and a compound formed from the
reaction is a dielectric stoichiometric material.
The method according to claim 1, wherein the sputter
deposition of a compound onto a substrate is performed at a rate at least about 40% of a rate of deposition of the target (18) material in a metallic mode
corresponding to operating without the presence of
said reactive gas at substantially the same power
conditions.
ical value of the control process parameter selected,
such that a given deposition rate and desired physical properties of films formed are achieved at arcing
below a given level.
5
9.
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11. A reactive sputter deposition apparatus, comprising:
The method according to claim 1, wherein said compound is selected from the group consisting of oxides, nitrides, oxynitrides, carbides, sulfides, fluorides, chlorides, borides, and mixtures thereof.
25
5.
The method according to claim 1, wherein said control process parameter is the target current in case
of continuous DC sputtering , or the average target
current in a period of a pulsed power supply (44) in
case of pulsed sputtering, or the reactive gas partial
pressure in a vacuum chamber (10).
30
7.
8.
The method according to claim 5, wherein the sensitivity of the target current in case of continuous DC
sputtering, or of the average target current in a period
of a pulsed power supply (44) in case of pulsed sputtering, and of the reactive gas partial pressure in a
vacuum chamber (10) to constant flow rate pulses
of the reactive gas into the vacuum chamber (10) at
a constant target voltage under the same discharge
conditions is determined.
The method of claim 6, wherein the parameter showing the highest sensitivity to constant flow rate pulses
of the reactive gas into the vacuum chamber (10) at
a constant target voltage under the same discharge
conditions is selected as control process parameter.
The method according to claim 1, wherein said operation regime is established based on determining
a constant target voltage, non-reactive gas,for example argon, partial pressure, total reactive gas flow
rate into the vacuum chamber and configuration of
the reactive gas conduit system, together with a crit-
The method according to claim 1, wherein said critical value of the said control process parameter defines the times of terminations and successive initiations of preset constant reactive gas flow rate pulses into the vacuum chamber (10).
10. The method according to claim 1, wherein said target
power is supplied at a constant target voltage using
a DC power supply or at a constant target voltage
during discharge pulses using a pulsed power supply, including a high power pulsed DC power supply
with target power densities of up to several kWcm-2
in short target voltage pulses.
4.
6.
14
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55
a vacuum chamber (10);
an anode;
a reactive gas source (26) that provides a reactive gas into the vacuum chamber (10), the reactive gas characterized by a given pulsed flow
rate into the chamber (10), maintained by mass
flow controllers, or by a given partial pressure in
the chamber (10), determined from a total gas
pressure in the chamber (10) measured at a
fixed preset value of the non-reactive gas partial
pressure;
a target (18) as a cathode in the vacuum chamber (10) and including a material to be combined
with reactive gas species to form a compound;
wherein the cathode is part of a magnetron sputter source,
a power supply (44) electrically coupled to said
target (18) such that said target may be selectively powered by the power supply (44) to generate a discharge plasma in the chamber (10)
with the reactive gas species that combine with
the material of the target (18) to form the compound;
a control device that senses time-dependent
values of said control process parameter and is
configured to provide a signal to said mass flow
controllers (28, 30) to adjust a pulsed reactive
gas flow rate into the vacuum chamber (10) at
a constant value of the non-reactive gas partial
pressure to perform a stabilized reactive deposition of dielectric stoichiometric films at high
rates and a minimized arcing in a transition region between a metallic mode and covered
mode.
12. The reactive sputter deposition apparatus, according to claim 11, wherein said target (18) is a metal
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EP 2 770 083 B1
Werte einzustellen.
and said compound is a dielectric stoichiometric material.
13. The reactive sputter deposition apparatus according
to claim 11, wherein said control device allows simultaneous monitoring in time both the reactive gas
partial pressure in said vacuum chamber (10), and
either the target current in case of continuous DC
sputtering or the average target current in a period
of a pulsed power supply in case of pulsed sputtering
to select one of them as said control process parameter for a given target material and reactive process
gas on the basis of a higher sensitivity of one of these
quantities to constant flow rate pulses of said reactive gas into said vacuum chamber (10) at a constant
target voltage under the same discharge conditions.
14. The reactive sputter deposition apparatus according
to claim 11, wherein said power supply (44) is a DC
power supply operating at a constant target voltage
or a pulsed power supply operating at a constant
target voltage during discharge pulses, including a
high power pulsed DC power supply with target power densities of up to several kWcm-2 in short target
voltage pulses, the pulsed power supplies possessing an internal or external computer control allowing
to evaluate a time-dependent average target current
in a period of the pulsed power supply during the
reactive gas flow rate pulsing.
2.
Verfahren nach Anspruch 1, wobei das Target (18)
ein Metall ist und eine aus der Reaktion entstandene
Verbindung ein dielektrisches stöchiometrisches
Material ist.
3.
Verfahren nach Anspruch 1, wobei die Sputterdeposition einer Verbindung auf ein Substrat mit einer
Rate stattfindet, die mindestens ungefähr 40% einer
Depositionsrate des Target (18)-Materials in einem
metallischen Modus entsprechend des Betriebs ohne die Anwesenheit des Reaktionsgases bei im Wesentlichen denselben Leistungsbedingungen beträgt.
4.
Verfahren nach Anspruch 1, wobei die Verbindung
ausgewählt ist aus der Gruppe bestehend aus Oxiden, Nitriden, Oxynitriden, Carbiden, Sulfiden, Fluoriden, Chloriden, Boriden und Mischungen davon.
5.
Verfahren nach Anspruch 1, wobei der Steuerprozessparameter beim kontinuierlichen DC-Sputtern
der Targetstrom, oder beim gepulsten Sputtern der
durchschnittliche Targetstrom in einer Periode einer
gepulsten Leistungsversorgung (44), oder der Reaktionsgas-Partialdruck in einer Vakuumkammer
(10) ist.
6.
Verfahren nach Anspruch 5, wobei die Sensitivität
des Targetstroms beim kontinuierlichen DC-Sputtern oder des durchschnittlichen Targetstroms in einer Periode einer gepulsten Leistungsversorgung
(44) beim gepulsten Sputtern, und des Reaktionsgas-Partialdrucks in einer Vakuumkammer (10) gegenüber konstanten Durchflussmengenpulsen des
Reaktionsgases in die Vakuumkammer (10) bei einer konstanten Targetspannung unter denselben
Entladebedingungen festgestellt wird.
7.
Verfahren nach Anspruch 6, wobei der Parameter,
der die höchste Sensitivität gegenüber konstanten
Durchflussmengenpulsen des Reaktionsgases in
die Vakuumkammer (10) bei einer konstanten Targetspannung unter denselben Entladebedingungen
aufweist, als Steuerprozessparameter gewählt wird.
8.
Verfahren nach Anspruch 1, wobei die Betriebsart
eingerichtet wird auf der Basis der Bestimmung einer
konstanten Targetspannung, Partialdruck eines
nicht reaktiven Gases, z.B. Argon, gesamte Durchflussmenge des Reaktionsgases in die Vakuumkammer und Anordnung des Leitungssystems für das
Reaktionsgas, zusammen mit einem kritischen Wert
des gewählten Steuerprozessparameters, so dass
eine gegebene Depositionsrate und gewünschte
physikalische Eigenschaften von gebildeten Filmen
erreicht werden und Lichtbogenbildung unterhalb ei-
5
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15
20
25
30
Patentansprüche
1.
Verfahren zum Steuern eines Magnetron-Sputterdepositionsprozesses umfassend die Reaktion zwischen Reaktionsgasspezies und einem Material,
das in einem Target (18) beinhaltet ist, das als eine
Kathode wirkt, wobei das Verfahren folgende Schritte aufweist:
16
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Auswählen eines Steuerprozessparameters für
ein gegebenes Targetmaterial und reaktives
Prozessgas;
Einrichten einer Betriebsart für einen reaktiven
Sputterdepositionsprozess für einen gegebenen nominalen Target-Leistungspegel; und
Durchführen einer reaktiven Deposition von dielektrischen stöchiometrischen Filmen in einem
Übergangsbereich zwischen einem metallischen Modus und einem beschichteten Modus
durch eine gesteuerte gepulste ReaktionsgasDurchflussmenge in die Vakuumkammer (10);
Feststellen von zeitabhängigen Werten des genannten Steuerprozessparameters und Bereitstellen eines Signals an die Massendurchflussregler (28, 30), um die gepulste ReaktionsgasDurchflussmenge in die Vakuumkammer (10)
auf der Basis der festgestellten zeitabhängigen
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55
9
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EP 2 770 083 B1
zwischen einem metallischen Modus und einem
beschichteten Modus auszuführen.
nes gegebenen Pegels bleibt.
9.
Verfahren nach Anspruch 1, wobei der kritische Wert
des Steuerprozessparameters die Endzeiten und
darauf folgende Startzeiten von voreingestellten
konstanten Reaktionsgas-Durchflussmengenpulsen in die Vakuumkammer (10) definiert.
10. Verfahren nach Anspruch 1, wobei die Targetleistung bei einer konstanten Targetspannung mittels
einer Gleichstromleistungsversorgung oder bei einer konstanten Targetspannung während Entladeimpulsen mittels einer gepulsten Leistungsversorgung, die eine Hochleistungs-gepulste-DC-Leistungsversorgung aufweist, mit Targetleistungsdichten von bis zu mehreren kWcm -2 in kurzen TargetSpannungspulsen, geliefert wird.
11. Reaktive
send:
Sputterdepositionsvorrichtung,
18
5
10
15
umfas-
eine Vakuumkammer (10);
eine Anode;
eine Reaktionsgasquelle (26), die ein Reaktionsgas in die Vakuumkammer (10) liefert, wobei
das Reaktionsgas durch eine gegebene gepulste Durchflussmenge in die Kammer (10) gekennzeichnet ist, die durch Massendurchflussregler beibehalten wird, oder durch einen gegebenen Partialdruck in der Kammer (10), bestimmt aus einem Gesamtgasdruck in der Kammer (10), der bei einem festen voreingestellten
Wert des Partialdrucks des nicht reaktiven Gases gemessen wird;
ein Target (18) als eine Kathode in der Vakuumkammer (10) und umfassend ein Material, das
mit einer Reaktionsgasspezies vereint wird, um
eine Verbindung zu bilden, wobei die Kathode
Teil einer Magnetron-Sputterquelle ist;
eine Leistungsversorgung (44), die mit dem Target (18) elektrisch gekoppelt ist, so dass das
Target selektiv von der Leistungsversorgung
(44) mit Leistung versorgt werden kann, um ein
Entladeplasma in der Kammer (10) mit den Reaktionsgasspezies zu erzeugen, die sich mit
dem Material des Targets (18) vereinen, um die
Verbindung zu bilden;
eine Steuervorrichtung, die zeitabhängige Werte der Steuerprozessparameter feststellt und so
ausgebildet ist, dass sie den Massendurchflussreglern (28, 30) ein Signal liefert, um eine gepulste Reaktionsgas-Durchflussmenge in die
Vakuumkammer (10) bei einem konstanten
Wert des Partialdrucks des nicht reaktiven Gases einzustellen, um eine stabilisierte reaktive
Deposition von dielektrischen stöchiometrischen Filmen bei hohen Raten und minimierter
Lichtbogenbildung in einem Übergangsbereich
20
12. Reaktive Sputterdepositionsvorrichtung nach Anspruch 11, wobei das Target (18) ein Metall und die
Verbindung ein dielektrisches stöchiometrisches
Material ist.
13. Reaktive Sputterdepositionsvorrichtung nach Anspruch 11, wobei die Steuervorrichtung das gleichzeitige zeitliche Überwachen sowohl des Reaktionsgas-Partialdrucks in der Vakuumkammer (10) als
auch entweder des Targetstroms bei kontinuierlichem DC-Sputtern oder des durchschnittlichen Targetstroms in einer Periode einer gepulsten Leistungsversorgung bei gepulstem Sputtern ermöglicht, um eines davon als den Steuerprozessparameter für ein gegebenes Targetmaterial und reaktives Prozessgas auf der Basis einer höheren Sensitivität einer dieser Größen gegenüber konstanten
Durchflussmengenpulsen des Reaktionsgases in
die Vakuumkammer (10) bei einer konstanten Targetspannung unter denselben Entladebedingungen
auszuwählen.
25
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40
14. Reaktive Sputterdepositionsvorrichtung nach Anspruch 11, wobei die Leistungsversorgung (44) eine
Gleichstromleistungsversorgung, die bei einer konstanten Targetspannung arbeitet, oder eine gepulste
Leistungsversorgung ist, die bei einer konstanten
Targetspannung während Entladeimpulsen arbeitet,
umfassend eine Hochleistungs-gepulste-DC-Leistungsversorgung mit Targetstromdichten von bis zu
mehreren kWcm-2 in kurzen Target-Spannungsimpulsen, wobei die gepulsten Leistungsversorgungen
eine interne oder externe Computersteuerung haben, die eine Auswertung eines zeitabhängigen
durchschnittlichen Targetstroms in einer Periode der
gepulsten Leistungsversorgung während des Pulsens der Reaktionsgas-Durchflussmenge erlaubt.
Revendications
45
50
55
10
1.
Procédé de commande d’un processus de dépôt par
pulvérisation cathodique par magnétron impliquant
une réaction entre des espèces de gaz réactifs et un
matériau inclus dans une cible (18) agissant comme
une cathode, ledit procédé comprenant les étapes
consistant à :
sélectionner un paramètre de processus de
commande pour un matériau cible et un gaz de
processus réactif donnés,
établir un régime de fonctionnement pour un
processus de dépôt par pulvérisation cathodique par magnétron pour un niveau de puissance
cible nominale donné, et
19
EP 2 770 083 B1
exécuter un dépôt de réactif de films stoechiométriques diélectriques dans une région de transition entre un mode métallique et un mode recouvert par le biais d’un débit de gaz réactif pulsé commandé dans la chambre à vide (10),
détecter des valeurs qui dépendent du temps
dudit paramètre de processus de commande et
fournir un signal à des contrôleurs de débit massique (28, 30) pour ajuster le débit de gaz réactif
pulsé dans la chambre à vide (10) sur la base
des valeurs qui dépendent du temps détectées.
2.
3.
Procédé selon la revendication 1, dans lequel ladite
cible (18) est un métal et un composé formé à partir
de la réaction est un matériau stoechiométrique diélectrique.
Procédé selon la revendication 1, dans lequel le dépôt par pulvérisation cathodique d’un composé sur
un substrat est exécuté à un débit d’au moins environ
40 % d’un débit de dépôt du matériau cible (18) dans
un mode métallique correspondant à un fonctionnement sans la présence dudit gaz réactif à pratiquement les mêmes conditions d’alimentation.
de.
5.
Procédé selon la revendication 1, dans lequel ledit
composé est sélectionné à partir du groupe constitué
d’oxydes, de nitrures, d’oxynitrures, de carbures, de
sulfures, de fluorures, de chlorures, de borures, et
de leurs mélanges.
Procédé selon la revendication 1, dans lequel ledit
paramètre de processus de commande est le courant cible dans le cas d’une pulvérisation cathodique
à courant continu continue, ou le courant cible
moyen dans une période d’une alimentation pulsée
(44) dans le cas d’une pulvérisation cathodique pulsée, ou la pression partielle de gaz réactif dans la
chambre à vide (10).
7.
Procédé selon la revendication 5, dans lequel la sensibilité du courant cible dans le cas d’une pulvérisation cathodique à courant continu continue, ou du
courant cible moyen dans une période d’une alimentation pulsée (44) dans le cas d’une pulvérisation
cathodique pulsée, et de la pression partielle de gaz
réactif dans une chambre à vide (10) pour des impulsions de débit constantes du gaz réactif dans la
chambre à vide (10) à une tension cible constante
dans les mêmes conditions de décharge est déterminée.
Procédé selon la revendication 6, dans lequel le paramètre présentant la sensibilité la plus élevée aux
impulsions de débit constantes du gaz réactif dans
la chambre à vide (10) à une tension cible constante
dans les mêmes conditions de décharge est sélectionné comme paramètre de processus de comman-
Procédé selon la revendication 1, dans lequel ledit
régime de fonctionnement est établi sur la base
d’une détermination d’une tension cible constante,
d’une pression partielle de gaz non réactif, par exemple l’argon, d’un débit de gaz réactif total dans la
chambre à vide et d’une configuration du système
de conduit de gaz réactif, ainsi qu’une valeur critique
du paramètre de processus de commande sélectionné, de sorte qu’une vitesse de dépôt et des propriétés physiques souhaitées données des films formés
soient obtenues avec un arc en dessous d’un niveau
donné.
9.
Procédé selon la revendication 1, dans lequel ladite
valeur critique dudit paramètre de processus de
commande définit les instants des fins et des débuts
successifs des impulsions de débit de gaz réactif
constantes préétablies dans la chambre à vide (10).
10
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20
30
10. Procédé selon la revendication 1, dans lequel ladite
puissance cible est fournie à une tension cible constante en utilisant une alimentation à courant continu
ou à une tension cible constante au cours d’impulsions de décharge en utilisant une alimentation pulsée, incluant une alimentation à courant continu pulsée à haute puissance avec des densités de puissance cibles jusqu’à plusieurs kWcm-2 dans des impulsions de tension cibles courtes.
11. Appareil de dépôt par pulvérisation cathodique par
magnétron, comprenant :
35
40
6.
8.
5
25
4.
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11
une chambre à vide (10),
une anode,
une source de gaz réactif (26) qui fournit un gaz
réactif dans la chambre à vide (10), le gaz réactif
étant caractérisé par un débit pulsé donné dans
la chambre à vide (10), maintenu par des contrôleurs de débit massique, ou par une pression
partielle donnée dans la chambre (10), déterminée à partir d’une pression de gaz totale dans
la chambre (10) mesurée à une valeur préétablie
fixe de la pression partielle de gaz non réactif,
une cible (18) en tant que cathode dans la chambre à vide (10) et incluant un matériau devant
être combiné avec des espèces de gaz réactifs
pour former un composé, dans lequel la cathode
fait partie d’une source de pulvérisation cathodique par magnétron,
une alimentation (44) couplée électriquement à
ladite cible (18) de sorte que ladite cible puisse
être sélectivement alimentée par l’alimentation
(44) pour générer un plasma de décharge dans
la chambre (10) avec les espèces de gaz réactifs
qui se combinent avec le matériau de la cible
(18) pour former le composé,
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EP 2 770 083 B1
un dispositif de commande qui détecte des valeurs qui dépendent du temps dudit paramètre
de processus de commande et est configuré
pour fournir un signal auxdits contrôleurs de débit massique (28, 30) pour ajuster un débit de
gaz réactif pulsé dans la chambre à vide (10) à
une valeur constante de la pression partielle de
gaz non réactif pour exécuter un dépôt réactif
stabilisé de films stoechiométriques diélectriques à des vitesses élevées et une formation
d’arc réduite au minimum dans une région de
transition entre un mode métallique et un mode
recouvert.
5
10
12. Appareil de dépôt par pulvérisation cathodique de
réactif, selon la revendication 11, dans lequel ladite
cible (18) est un métal et ledit composé est un matériau stoechiométrique diélectrique.
15
13. Appareil de dépôt par pulvérisation cathodique de
réactif selon la revendication 11, dans lequel ledit
dispositif de commande permet une surveillance simultanée dans le temps à la fois de la pression partielle de gaz réactif dans ladite chambre à vide (10),
et soit du courant cible dans le cas d’une pulvérisation cathodique à courant continu continue soit du
courant cible moyen dans une période d’une alimentation pulsée dans le cas d’une pulvérisation pulsée
pour sélectionner l’un d’entre eux comme ledit paramètre de processus de commande pour un matériau cible et un gaz de processus réactif donnés sur
la base d’une sensibilité plus élevée de l’une de ces
quantités à des impulsions de débit constantes dudit
gaz réactif dans ladite chambre à vide (10) à une
tension cible constante dans les mêmes conditions
de décharge.
20
14. Dispositif de dépôt par pulvérisation cathodique de
réactif selon la revendication 11, dans lequel ladite
alimentation (44) est une alimentation à courant continu fonctionnant à une tension cible constante ou
une alimentation pulsée fonctionnant à une tension
cible constante au cours d’impulsions de décharge,
incluant une alimentation à courant continu pulsée
à haute puissance avec des densités de puissance
cibles jusqu’à plusieurs kWcm-2 dans des impulsions
de tension cibles courtes, les alimentation pulsée
possédant une commande informatique interne ou
externe pour évaluer un courant cible moyen qui dépend du temps dans une période de l’alimentation
pulsée au cours de l’impulsion de débit de gaz réactif.
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30
35
40
45
50
55
12
22
EP 2 770 083 B1
13
EP 2 770 083 B1
14
EP 2 770 083 B1
15
EP 2 770 083 B1
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European
patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be
excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description
•
•
WO 2007147582 A1 [0006]
WO 2009071667 A1 [0007]
•
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WO 2010125002 A1 [0008]
EP 1553206 A1 [0009]
•
LAZAR, J. et al. ion flux characteristics and efficiency
of the deposition processes in high power impulse
magnetron sputtering of zirconium. JOURNAL OF
APPLIED PHYSICS, AMERICAN INSTITUTE OF
PHYSICS, 2 HUNTINGTON QUADRANGLE,
MELVILLE, NY 11747, 28 September 2010, vol. 108
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Non-patent literature cited in the description
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MARTIN, N. et al. High rate and process control of
reactive sputtering by gas pulsing: The Ti-O system.
THIN SOLID FILMS, 01 December 2000, vol. 377 378, 550-556 [0010]
16